Background
Childhood obesity is a serious public health problem worldwide [
1-
3] affecting low and middle income families [
4]. During childhood and adolescence, being obese or overweight may lead to physical, psychological, and social health problems [
5-
11]. These health conditions may persist through adulthood [
12], contributing to a significantly lower health-related quality of life [
13]. Moreover, obesity/overweight associated-health conditions are related to the primary causes of mortality worldwide [
14-
16]. The burden of cardiovascular disease (CVD) for Puerto Ricans is substantial. Cardiometabolic risk refers to the probability of having diabetes, heart disease or stroke [
17]. For U.S. residing Puerto Ricans approximately 18% of the adults had diabetes, 28% hypertension, and 45% hypercholesterolemia, as examples of metabolic conditions [
18]. For Puerto Ricans residing in the island, 13.5% self-reported diabetes, 37% had hypertension, and 38% hypercholesterolemia, among other CVD factors [
19].
The worldwide prevalence of childhood overweight and obesity increased 10% between 1990 and 2010 [
20]. During the last 30 years, childhood obesity in the US has more than doubled and has quadrupled in adolescents [
21,
22]. The 2011–2012 National Health and Nutrition Examination Survey (NHANES) [
22] states that 34.5% of the 12–19 year-olds were obese or overweight and 20.5% were obese. In this report, obesity was higher among non-Hispanic black and Hispanic children as well as adolescents compared to non-Hispanic white children. Obesity rates of Puerto Rican children in mainland US and in PR are among the highest (24-36%) when compared to other racial/ethnic groups [
23]. An island-wide study conducted among 3,079 second graders established the prevalence of at risk of overweight at 16% and of overweight at 26% [
24]; these categories are currently termed overweight and obese, respectively [
25]. In another investigation, the combined self-reported prevalence of overweight and obesity in 10–19 year-olds in PR was 34.9% while in 10–14 year-olds was 52.3% [
26]. Moreover, a study of 250 elementary school children in PR revealed that 26.8% were obese and 11.3% were overweight [
27]. These previous studies employed convenient samples of limited size in specific communities except the study conducted among second graders [
24], which was published as a government report in Spanish.
In the U.S., Healthy People 2020 established targets to guide the health promotion and disease prevention efforts [
28] and to reduce obesity in children and adolescents [
29]. In PR, the only island-wide study, on childhood obesity was conducted in 2005 [
24]; therefore, no ongoing surveillance program exist posing a challenge to monitor changes and control these conditions. The objectives of the study are: 1) to establish the BMI prevalence in 12-year olds residing in Puerto Rico, and 2) to determine BMI differences by sex, public-private school type, and geographic regions.
Results
A total of one thousand five hundred and eighty two (n = 1,582) subjects were evaluated between November 2010 and May 2011. The distribution of the demographic characteristics of gender and type of school attended were as follows: 53% females, 47% males; 77.2% public schools, 22.8% private schools. The distribution in relation to the school’s region was: North (10.5%), Northwest (4.9%), Northeast (6.0%), East (8.2%), Southeast (9.0%), Southwest (5.2%), Ponce (4.3%), West (4.9%), Metro area (22.8%), San Juan (10.3%) and Mountain (14.0%). By zones, the distribution was: Coast (n = 837; 52.9%), Metropolitan (n = 523; 33.1%) and Central Mountain (n = 222; 14.0%).
The estimated prevalence and 95% confidence intervals (CI) for each BMI category are shown in Table
1. Overall, the prevalence of obesity was 24.3% (CI: 19.9%, 29.2%) and for overweight it was 18.8% (CI: 16.4%, 20.3%). A higher prevalence of obesity was seen in boys (28.2%, CI: 18.7%, 40.1%) than in girls (20.2%, CI: 19.5%, 29.2%). In terms of school type, children in public schools had a lower prevalence of overweight (18.6%, CI: 15.4%, 22.4%) and obesity (24.0%, CI: 19.5%, 29.2%), when compared to children in private schools (overweight 21.2%, CI: 16.4%, 27.1%; obese 28.2%, CI: 18.7%, 40.1%).
Table 1
Estimated Prevalence and 95% CI of Underweight, Healthy Weight, Overweight, and Obesity by Gender and School Type
Overall n=1,582 | 2.7% (1.8, 4.1)2 | 3.0% (2.3, 4.0) | 54.3% (50.2, 58.3) | 55.5% (53.0, 57.9) | 18.8% (16.4, 20.3) | 18.3% (16.4, 20.3) | 24.3% (19.9, 29.2) | 23.2% (21.2, 25.3) |
n=48
|
n=878
|
n=289
|
n=367
|
Gender | Boys n=744 | 2.7% (1.7, 4.4) | 3.9% (2.7, 5.6) | 50.1% (44.2, 56.0) | 52.7% (49.1, 53.7) | 18.5% (14.9, 22.6) | 17.3% (14.8, 20.2) | 28.2% (18.7, 40.1) | 26.1% (23.1, 29.4) |
n=29
|
n=392
|
n=129
|
n=194
|
Girls n=838 | 2.7% (1.6, 4.4) | 2.3% (1.5, 3.5) | 58.1%(53.1, 62.9) | 58.0% (54.6, 61.3) | 19.0% (14.6, 22.3) | 19.1% (16.4, 21.8) | 20.2% (19.5, 29.2) | 20.6% (18.0, 23.5) |
n=19
|
n=486
|
n=160
|
n=173
|
School Type | Public n=1,221 | 2.7% (1.8, 4.2) | 3.3% (2.4, 4.4) | 54.6% (50.3, 58.8) | 56.4% (53.5, 59.1) | 18.6% (15.4, 22.4) | 18.6% (15.4, 22.4) | 24.0% (19.5, 29.2) | 22.4% (20.1, 24.8) |
n=40
|
n=688
|
n=220
|
n=273
|
Private n=361 | 2.1% (1.0, 4.3) | 2.2% (1.1, 4.4) | 48.5% (35.9, 61.3) | 52.6% (47.5, 57.7) | 21.2% (16.4, 27.1) | 19.1% (15.4, 23.5) | 28.2% (18.7, 40.1) | 26.0% (21.8, 30.8) |
n=8
|
n=190
|
n=69
|
n=94
|
Table
2 shows the estimated prevalence of overweight and obesity stratified by type of school and gender. In private schools, more boys were overweight (26.6%, CI: 15.3%, 38.1%) than in public schools (17.9%, CI: 13.9%. 21.9%). Girls from private schools had a lower prevalence of overweight (15.1%, CI: 8.97%, 21.3%) than those in public schools (19.2%, CI: 14. 8%, 23.7%); while obesity prevalence in girls from private schools (27.8%, CI: 15.9%, 39.7%) was higher compared to those attending public schools (19.8%, CI: 15.4%, 24.3%). This difference was not observed in boys.
Table 2
Estimated Prevalence of Underweight, Healthy Weight, Overweight, and Obese by Gender and School Type
Underweight n = 48 | Boys n = 29 | 2.8% (1.37, 4.20)2 | 4.4% (2.89, 5.96) | 2.0% (0.035, 4.01) | 2.2% (0.32, 4.15) |
n = 25
|
n = 4
|
Girls n = 19 | 2.7% (1.27, 4.11) | 2.3% (1.23, 3.33) | 2.2% (−0.17, 4.55) | 2.2% (1.72, 4.22) |
n = 15
|
n = 4
|
Healthy Weight n = 878 | Boys n = 392 | 50.6% (44.38, 56.87) | 53.6% (49.20, 58.05) | 42.8% (24.84, 60.72) | 49.7% (41.17, 58.27) |
n = 303
|
n = 89
|
Girls n = 486 | 58.2% (53.04, 63.44) | 58.7% (54.62, 62.76) | 54.9% (42.17, 67.66) | 55.5% (48.47, 62.52) |
n = 385
|
n = 101
|
Overweight n = 289 | Boys n = 129 | 17.9% (13.94, 21.92) | 16.4% (13.5, 19.34) | 26.7% (15.25, 38.07) | 20.1% (13.93, 26.29) |
n = 93
|
n = 36
|
Girls n = 160 | 19.2% (14.75, 23.74) | 19.4% (16.45, 22.29) | 15.1% (8.97, 21.27) | 18.1% (13.34, 22.92) |
n = 127
|
n = 33
|
Obesity n = 367 | Boys n = 194 | 28.7% (21.76, 35.57) | 25.5% (21,79 29.18) | 28.5% (16.63, 40.44) | 27.9% (20.11, 35.75) |
n = 144
|
n = 50
|
Girls n = 173 | 19.8% (15.35, 24.30) | 19.7% (16.13, 23.01) | 27.8% (15.87, 39.68) | 24.2% (17.96, 30.39) |
n = 129
|
n = 44
|
Boys were at a significantly higher risk (POR
weighted =1.64, CI: 1.18, 2.35) of being obese compared to girls, after adjusting for type of school and region. No other statistical differences were observed (Table
3).
Table 3
Weighted Prevalence Odd-ratios
(POR
weighted
)
for obese or overweight vs. healthy weight and socio-demographic variables (n = 1534)
1
Gender
| Boys4 | 1.12 (0.80, 1.58) | 1.11 (0.79, 1.57) | 1.64 (1.18, 2.29) | 1.66 (1.17, 2.35) |
School type
| Public5 | 0.78 (0.47, 1.30) | 0.81 (0.50, 1.32) | 0.76 (0.38, 1.50) | 0 .72 (0.37, 1.42) |
Zone
| Metro6 | 1.23 (0.604, 2.51) | 1.20 (0.58, 2.46) | 0.74 (0.33, 1.65) | 0.65 (0.31, 1.37) |
Coast6 | 1.20 (0.56, 2.57) | 1.18 (0.55, 2.56) | 0.67 (0.32, 1.39) | 0.69 (0.30, 1.58) |
Children in the East, Northeast and Southwest regions had the highest estimated prevalence of overweight (≥19.5%), while the Southeast and Northwest regions had the lowest (14.1% and 14.3%, respectively). The highest obesity prevalence was found in the Northeast region (33.7%), followed by Northwest region (25.9%), and Ponce (25.0%). The lowest was observed in the Mountain and Southwest regions (19.4% and 19.5%, respectively).
Discussion
The aim of this study were to establish the BMI prevalence in 12-year olds residing in Puerto Rico, and to determine BMI differences by sex, public-private school type, and geographic regions.. We found that the overweight prevalence was 18.8%, which is higher than those reported in prior studies in Puerto Rican children aged 7 years (16.2%) [
24] and 9–10 years (11.3%) [
27]. The overall prevalence of obesity was 24.3%, which is slightly lower than the prevalence reported in the aforementioned studies in PR (25.7% and 26.8%) [
24] [
27]. The obesity prevalence in PR, as presented by this study, is higher than the overall prevalence in U. S. for 12-19-year-olds (20.5%) and higher when stratified by race/ethnicity (whites 19.6%, non-Hispanic blacks 22.1%, and Hispanics 22.6%) [
38]. Overweight prevalence in the U.S. was presented together with obesity data, precluding its comparison [
38]. The prevalence of underweight in this study (2.7%) is slightly lower than in the US (3.6%) [
39].
The current study portrayed boys with a higher prevalence of obesity but similar prevalence of overweight when compared to girls while boys were at significantly higher risk of being obese compared to girls. A previous study in PR found that boys had a higher prevalence of obesity compared to girls (26.9% vs. 24.5%); however, the overweight prevalence for girls was higher than for boys (17.4% vs. 14.8%) [
24]. This finding is similar to a recent study in 436 Puerto Ricans aged 10–19 years [
26], whereas it was reported that females were 50% less likely than males to be overweight or obese. The current study’s results are consistent with US national data from NHANES 2009–10, where male children and adolescents from all racial/ethnic groups had higher obesity prevalence compared to females [
40].
The obesity prevalence data from NHANES 2011–12 [
22] showed no differences in gender when all races/Hispanic origin groups were considered. The exception was between Hispanics and non-Hispanic Asian boys, who had higher obesity prevalence when compared to girls; however, these differences were not statistically significant. Worldwide data indicates that adolescent boys have higher prevalence of obesity in almost all nations and higher prevalence of overweight in almost half of the countries compared to girls [
3]. Weight differences between boys and girls may be related to awareness of weight control and to body image issues that may develop in pre-adolescence [
41].
Regarding the type of school attended, children from private schools had a higher prevalence of overweight and obesity than those attending public schools. The results are consistent with those of the 2005 island-wide study [
24] where children attending private schools had a higher BMI than those attending public school. It is possible that children who attend private school, a surrogate (indication?) to higher socioeconomic status in PR, have higher purchasing power to consume sweets, snacks, and fast foods more often. These findings may be also attributed to the existence of the National School Lunch Program (NSLP) in the public school system, which is not available in most private schools. It has been reported that children participating in the NSLP have lower prevalence of overweight and obesity than non-participating children [
42]. NSLP provides nutritionally balanced meals for lunch, which could be beneficial in reducing the risk of overweight and obesity.
Overall, we observed a higher risk of obesity in boys as compared to girls. When stratified by gender and type of school, the study suggests a high prevalence of obesity in boys in both public and private schools; however, girls from private schools had higher obesity prevalence than those in public schools. In contrast, the percentage of overweight girls attending public school was higher but no significantly different than those attending private school. Similarly, the study conducted in Cayey, PR, reported a higher prevalence of obese/overweight in girls from private schools compared to girls from public schools [
27]. Another study in children and adolescents attending public schools in the San Juan Metropolitan Area reported that girls had a better diet compared to boys due to their higher participation rate in the NSLP [
43]. Therefore, participation in the NSLP program provides an alternative explanation for the weight differences between boys and girls in PR.
A recent study conducted in the San Juan Metropolitan area found that girls had significantly higher scores for whole fruits and vegetables than boys [
44]. In addition, overweight/obese children had a significantly lower availability of unhealthy foods at home, higher access to home recreational/sport facilities, lower use of school recreational/sport facilities, but reduced participation in school breakfast programs (SBP). The authors concluded that all participants had either poor diet or a diet that was not adequate [
45]. Although the diet data was obtained by interviews with trained nutritionist, the availability and access to healthy or unhealthy foods and to sports and recreation was obtained through self-reported nutrition questionnaires. More research is needed to assess the factors associated with overweight/obesity and to assess the contribution of the SBP, NSLP, and other dietary habits on caloric intake and meal quality offered in private schools and health regions.
Our study revealed that the highest obesity prevalence was found in the Northeast, Northwest, and Ponce regions of PR, and the lowest prevalence in the Mountain and Southwest regions. Our findings are in partial agreement with an island-wide study conducted in a representative sample of second graders. In this study, the highest obesity prevalence was found in the municipalities located in the Eastern and Northern regions; the lowest prevalence was observed in the Metropolitan area [
24]. Body weight differences among regions may be due to local environmental factors such as the availability of healthy and unhealthy foods and food outlets as well as the accessibility of recreational/sports facilities and physical activity programs at home and school [
46-
48]. Unfortunately, the difference in the number of health regions and their geographical boundaries prevent an in-depth comparison between the two studies.
According to the 2010–11 U.S. Census, 45.6% of Puerto Ricans households fall below the poverty level [
49]. Health inequalities exist and persist between Puerto Ricans residing in the island and US citizens in the mainland. For example, even though the prevalence of obesity/obesity-related diseases is higher in PR [
50], the island does not have an ongoing surveillance program to project 2020 obesity trends in school-age children. Considering NHANES historical trends in obesity (1971–2008), US children are projected in 2020 to be 1.8 kg heavier than a child in 2007–2008, and adolescents to be 2.7 kg heavier than adolescents during this period. It has been estimated that a child should reduce his/her caloric intake by 164–286 kcal/day, depending on their race-ethnicity, to achieve the goals of Healthy People 2020 [
51]. Currently, the daily caloric intake required to meet these goals cannot be determined in PR. To define the appropriate reduction in caloric intake for Puerto Rican children, it is necessary to determine obesity trends and future projections. Risk factors including diet, physical activity, and other behavioral, social and physical environmental health determinants need to be investigated to better understand the complexity of obesity in Puerto Rican children to reduce this gap. Further investigation is needed to determine the social, physical and environmental factors related to this public health problem, allowing designing suitable policies and programs to reduce the prevalence of overweight and obesity.
One of the strengths of this study is the inclusion of a large and representative sample of 12-year-olds residing in PR. The interviewers and personnel conducting the anthropometry were trained using standardized methods. One of the limitations in regards to obesity is that the sampling was designed to estimate oral health outcomes; in consequence, important risk factors including dietary/snacking habits and physical activity of the child, as well as potential parental correlates, e.g., weight/obesity status were not investigated as study variables. However, with no contemporary anthropometric data on children in PR, island-wide, population-base BMI data is of importance for the public health community. Further investigation of these important obesity risk factors is required. When stratified by gender and type of school/region, some of the strata had limited number of subjects. Since BMI is not a good indicator of visceral obesity, future studies should include other anthropometric measurements including waist circumference, a simple and inexpensive method.
This island-wide study provides current data on the magnitude of the childhood overweight and obesity epidemic in PR. Our findings may contribute in mobilizing resources for the design of studies to identify successful policies and interventions.
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Competing interests
The authors declare that they have no competing interests.
Authors’ contributions
ARE conceived of the study, participated in its design and coordination and gave the final approval of the version to be published. MJT participated in drafting the manuscript and revising it critically for intellectual content. OG, participated in the design of the study, performed the statistical analysis, and helped to draft the manuscript. RT helped to draft the manuscript. CP made substantial contribution to conception and design helped to draft and revise critically the manuscript. All authors have read and approved the final manuscript.